Sitting time is negatively related to microvascular endothelium-dependent function in rheumatoid arthritis

Background
Sedentary behaviour is linked to increased cardiovascular disease risk in Rheumatoid Arthritis (RA), but the biological processes underlying this relationship are not understood.
Objectives
To investigate the cross-sectional associations of habitual sedentary behaviour, with endothelial function in RA.
Methods
Sixty-eight RA patients (Mage = 55 ± 12 years) underwent Laser Doppler Imaging with iontophoresis, to assess microvascular endothelium-dependent (acetylcholine, ACh) and endothelium-independent (sodium nitroprusside, SNP) function. Large-vessel endothelium-dependent and endothelium-independent functions were measured via flow-mediated dilation (FMD) and glyceryl trinitrate dilation (GTN), respectively. Habitual sedentary behaviour (hours/week sitting) was self-reported (International Physical Activity Questionnaire).
Results
Regressions revealed sitting time significantly negatively predicted microvascular endothelium-dependent function (ACh, unstandardizedβ = −3.25, p = .02, 95% CI [−6.07, −.42], R2 = 0.06), but did not associate with other endothelial function outcomes (SNP, FMD, GTN).
Conclusion
Habitual sedentary behaviour (sitting time) appears to be adversely linked to microvascular endothelium-dependent function among people living with RA.